Such eyeglass frames have been disclosed in published French patent application No. 2,094,810 and U.S. Pat. No. 3,713,732 and have the advantage of simplifying the mounting or positioning of the ophthalmic lenses therefor. Indeed the mounting of the lenses may be carried out in a single operation, and/or facilitate the changing, at will, of such ophthalmic lenses depending on the conditions of use, near or far vision, and/or the ambient lighting conditions. A single main frame structure may be utilized for supporting various frame fronts each of which may be separately stored more compactly than entire eyeglasses or spectacles.
But the practical embodiments of such eyeglass frames proposed to date, particularly in the aforesaid patents does not satisfy the usual aesthetic and convenience desiderata. The arrangement with a threaded fastener in French printed patent application No. 2,094,810 is unreliable and the aesthetics of the eyeglass disclosed in U.S. Pat. No. 3,713,732 is not to everyone's taste.